body {
    margin: 0;
    font-family: Arial, sans-serif;
}

.navbar {
    position: relative;
    width: 100%;
    overflow: hidden;
    background-color: #333; /* 添加背景颜色以便更好地显示导航条 */
}

#navImage {
    width: 100%;
    height: 0;
    transition: height 5s ease-in-out;
}

#navImage.show {
    height: 400px;
}

#hideButton {
    position: absolute;
    top: 10px;
    right: 10px;
    padding: 10px 20px;
    background-color: #ff0000;
    color: white;
    border: none;
    cursor: pointer;
}